For environmental improvement, pollution prevention, and the like, a honeycomb structure is frequently used as a trapping filter for exhaust gas. At present, for example, a SiC DPF (diesel particulate filter) is manufactured by unitarily bonding divided substrate (honeycomb segment) with a bonding material (e.g., ceramic cement) in order to avoid cracking due to thermal shock (see, e.g., Patent Document 1).
In the case of manufacturing such a honeycomb segment, there has been used a honeycomb segment-forming die provided with an introducing portion arranged on one face (introduction face) side and having a plurality of back holes and a forming portion arranged on the other face (formation face) side and having slits communicating with the back holes to form a honeycomb segment by passing kneaded clay for forming introduced from the back holes of the introducing portion through the slits in the forming portion.
As described above, since honeycomb segments are used by being unitarily joined with one another with a bonding material, each honeycomb segment is generally formed to have a prismatic shape (e.g., quadrangular prismatic shape and hexagonal prismatic shape). Therefore, a honeycomb segment-forming die for forming a honeycomb segment is constituted in such a manner that the forming portion has a polygonal outer peripheral shape. In addition, such a honeycomb segment-forming die is generally constituted in such a manner that the gaps of slits in the forming portion are uniform.
Patent Document 1: JP-A-2003-10616